The present device relates to a semiconductor component, or more particularly to a structure of a voltage regulator which can implement an output current of a desired output level by a change of only an output transistor without a necessity of making a new mask for the IC.
In general, a photo-masking process in the semiconductor manufacturing process, an important field in the semiconductor manufacturing process, is a technique for selectively removing the uppermost layer of a wafer or for forming a pattern. The photo masking process is also used in the case of forming a voltage regulator chip. In other words, the operation of laying out the mask with formation of a pattern onto the surface of a wafer and radiating the same with the light source is repeated. The repeated operations are different according to the types of chips. For the voltage regulator, about 7 to 10 masks are used sequentially.
The voltage regulator has a function of keeping an output voltage constant even when an input voltage and an output current are changed, wherein a drive IC and an output transistor, etc are included in a chip.
FIG. 2 is a drawing for showing a structure of a conventional voltage regulator. A plural of lead frames 51, 53, 55 for outputting the voltage, for grounding and for inputting the voltage (or the current) respectively are shown in the Figure, and a chip 57 is mounted on the lead frame 51 for the output of the voltage. The chip 57 is formed as an one-chip form where the drive IC and the output transistor are laid out in one chip. The chip 57 can be connected electrically, if necessary, to the lead frames 53, 55 laid out adjacently. Also, the chip 57 and the lead frames 51, 53, 55 are molded as a package 59.
According to the one-chip form voltage regulator constructed as above, the input voltage is inputted to the lead frame 55 for an input operation, and a constant voltage is outputted through the lead frame 51 for an output operation by operations of the drive IC and the output transistor.
In the conventional one-chip form voltage regulator, all the masks must be separately produced in the IC manufacture process in the case for varying the level of the output current. Accordingly, when an IC is made with the varying output current, a new mask must be made according to the corresponding output current, thereby increasing the manufacture costs.
For solving the problem mentioned above, the present device provides a voltage regulator, wherein the existing masks can be used unchanged even in case of changing the output current of the voltage regulator, and the chips are made in smaller size to be mounted on the lead frames of a smaller area, thereby reducing the manufacturing costs.
To accomplish the object of the present device mentioned above, the voltage regulator comprises a lead frame comprising a multiple of leads, a drive IC mounted on the lead frame, and an output transistor which is formed as a separate chip from the drive IC and is connected electrically to the drive IC, said output transistor being mounted on the lead frame to determine the load current.